The invention relates to a delivery device for delivering fuel from a fuel tank to an internal combustion engine of a motor vehicle, having a delivery pump and having a flow line which is connected to the delivery pump and having a fuel filter which is arranged in the flow line.
Delivery devices of this type are frequently used in motor vehicles today and are known in practice. The fuel filter here is arranged within the fuel tank in order to reduce any escape of fuel into the environment. Therefore, when the fuel filter is replaced, a service opening of the fuel tank has to be opened. However, a large amount of fuel escapes into the surroundings through the service opening and the seal to the fuel tank.
The invention is based on the problem of designing a delivery device of the type mentioned at the beginning in such a manner that delivery of fuel after the fuel filter has been clogged with dirt is reliably ensured, and that it largely prevents any escape of fuel into the surroundings.
According to the invention, this problem is solved in that the flow line has a bypass line which is conducted past the fuel filter, and in that means are provided for closing the bypass line in the original state and opening up the bypass line after a designated period of use or stage of wear of the fuel filter.
This design allows the fuel filter which has become clogged with dirt simply to remain within the fuel tank. The fuel is then conducted past the fuel filter. Reliable delivery of fuel is therefore ensured. A service opening of the fuel tank is therefore not required. This largely prevents any escape of fuel into the surroundings.
According to another advantageous development of the invention, the fuel which is conducted past the fuel filter can be filtered in a simple manner if a second fuel filter is arranged in the bypass line.
A contribution is made to further reducing the escape of fuel if the means for closing and opening up the bypass line are intended for arrangement within the fuel tank.
According to another advantageous development of the invention, the number of sealing points on the outside of the fuel tank can be kept particularly small if the bypass line and that region of the flow line which leads through the fuel filter are brought together within the fuel tank.
When a fuel filter has become clogged with dirt, a further fuel filter can be arranged on the outside of the fuel tank if the bypass line and that region of the flow line which leads through the fuel filter each have a connection on the outside of the fuel tank, and if the bypass line has a blind plug. This design keeps any escape of fuel into the environment particularly small over the entire operating period of the fuel filter which is arranged within the fuel tank. In order to keep the pollution of the environment with fuel particularly low, it is, of course, also possible for a plurality of fuel filters to be arranged in the fuel tank. The bypass line which is provided with the blind plug is used exclusively to avoid replacing the fuel tank when all of the fuel filters arranged in the fuel tank have become clogged.
According to another advantageous development of the invention, the means for closing and opening up the bypass line prove to be structurally particularly simple if they have a switch-over valve arranged in the flow line.
For example, the switch-over valve may be actuated manually if the delivery of fuel fails. According to another advantageous development of the invention, a spontaneous interruption to the delivery of fuel can be avoided in a simple manner by means for actuating the switch-over valve after a designated time interval or a designated kilometer reading of the motor vehicle.
The control of the means for closing and opening up the bypass line requires a particularly low constructional outlay if the means for closing and opening up the bypass line can be activated by the pressure upstream of the fuel filter.
According to another advantageous development of the invention, the switch-over valve proves to be structurally particularly simple if it has a closing body which is designed such that it can be displaced longitudinally.
The control of the switch-over valve may, for example, take place manually or under electrical control. However, according to another advantageous development of the invention, the activation of the switch-over valve requires a particularly low outlay if the movement of the closing body can be controlled as a function of the pressure of the delivery pump.
According to another advantageous development of the invention, the switch-over valve can be controlled electrically or manually with a particularly low constructional outlay if the switch-over valve has a rotatably closing body.